Semiconductor exposure device using extreme ultra violet radiation

ABSTRACT

The exposure device is able to supply only EUV radiation to a mask, while eliminating radiation other than the EUV radiation. A multi layer made from a plurality of Mo/Si pair layers is provided upon the front surface of a mirror, and blazed grooves are formed in this multi layer. Radiation which is incident from a light source device is incident upon this mirror, and is reflected or diffracted. Since the reflected EUV radiation (including diffracted EUV radiation) and the radiation of other wavelengths are reflected or diffracted at different angles, accordingly their directions of progression are different. By eliminating the radiation of other wavelengths with an aperture and/or a dumper, it is possible to irradiate a mask only with EUV radiation of high purity.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. Application Ser. No.12/469,176, filed on May 20, 2009, now U.S. Pat. No. 8,227,778, claimingpriority of Japanese Patent Application Nos. 2008-226548, filed on Sep.4, 2008 and 2008-132479, filed on May 20, 2008, the entire contents ofeach of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION Technical Field

The present invention relates to a semiconductor exposure device whichuses extreme ultra violet radiation.

For example, a semiconductor chip may be created by projecting a maskupon which a circuit pattern is drawn, in reduced form, upon a wafer towhich a resist has been applied, and by repeatedly performing processingsuch as etching and thin layer formation and so on. Along with theprogressive reduction of the scale of semiconductor processing, the useof radiation of progressively shorter and shorter wavelengths isrequired.

Thus, research is being performed into a semiconductor exposuretechnique which uses radiation of extremely short wavelength, such as13.5 nm, and a reducing optical system. This type of technique is termedEUV-L (Extreme Ultra Violet Lithography: exposure using extreme ultraviolet radiation). Hereinafter, extreme ultraviolet will be abbreviatedas “EUV”. An EUV exposure system which uses EUV radiation includes alight source device which outputs EUV radiation and an exposure devicewhich irradiates this EUV radiation upon a mask, thus creating a circuitpattern upon a semiconductor wafer (for example, refer to PatentReference #1).

Three types of EUV light sources are known: an LPP (Laser ProducedPlasma: plasma produced by a laser) type light source; a DPP (DischargeProduced Plasma: plasma produced by a discharge) type light source; andan SR (Synchrotron Radiation) type light source. An LPP type lightsource is a light source which generates a plasma by irradiating laserradiation upon a target substance, and which employs EUV radiationemitted from this plasma. A DPP type light source is a light sourcewhich employs a plasma generated by an electrical discharge. And a SRtype light source is a light source which employs radiation emitted fromtracks in a synchrotron. Among these three types of light source, thereare better possibilities for obtaining EUV radiation of high output withan LPP type light source as compared to the other methods, since such alight source can provide increased plasma density, and since moreoverthe solid angle over which the radiation is collected can be made large.

Since EUV radiation has a very short wavelength and can easily beabsorbed by matter, accordingly the EUV-L technique uses a reflectiontype optical system. Such a reflection type optical system may be builtby employing a multi layer in which, for example, molybdenum (Mo) andsilicon (Si) are used. Since the reflectivity of such an Mo/Si multilayer is high in the vicinity of 13.5 nm, accordingly EUV radiation of13.5 nm wavelength is used in the EUV-L technique.

However, since the reflectivity of such a multi layer is around 70%,therefore the output gradually decreases as the number of reflectionsincreases. Since the EUV radiation is reflected several tens of timeswithin the exposure device, accordingly it is necessary for the EUVlight source device to supply EUV radiation to the exposure device atrather high output. Thus, it is expected that the use of LPP type lightsources as EUV light source devices will become more common (refer toPatent Reference #2). With an LPP type light source device, liquiddroplets of tin (Sn), for example, are supplied as targets within avacuum chamber from a target supply device, these liquid droplets of tinare converted into plasma by being irradiated with radiation from acarbon dioxide gas laser, and the radiation which is emitted from thisplasma is collected by a collector mirror and is conducted to theexposure device.

Now, in an EUV exposure system, it is necessary to supply EUV radiationof rather high purity to the exposure device. If radiation other thanEUV radiation is mixed into the radiation which is irradiated upon themask, then the exposure contrast may be decreased, so that the accuracyof the patterning is deteriorated. For example, the exposure resistwhich is used in the exposure device is photosensitive to radiation inthe wavelength region from 130 nm (DUV: Deep Ultraviolet) to 400 nm (UV:Ultraviolet), so that, if a substantial amount of such radiation ispresent in the spectrum of the radiation which is emitted from theplasma, this will cause deterioration of the exposure contrast.Moreover, if infrared radiation (IR: Infrared) is present in theradiation from the plasma, then this IR will be absorbed by the mask andthe wafer and so on and will cause thermal expansion, so that there is apossibility that the accuracy of the patterning will be decreased.

In particular, in the case of an EUV light source device which uses acarbon dioxide gas pulse laser which emits infrared radiation ofwavelength 10.6 μm (hereinafter termed a “CO₂ laser”) as a light sourcefor exciting a target consisting of tin, since some of the high outputof CO₂ laser radiation is scattered and reflected by the target,accordingly it is necessary to eliminate this scattered CO₂ laserradiation. For example, if the intensity of the EUV radiation centeredaround the wavelength of 13.5 nm is taken as unity, then it is necessaryto keep down the intensity of the CO₂ laser radiation included thereinto 0.01 or less.

Thus, in a third prior art technique (refer to Patent Reference #3), areflective type planar diffraction lattice is provided which separatesthe EUV radiation from radiation of other wavelengths, and only the EUVradiation is supplied. The radiation of other wavelengths outside theEUV region is absorbed by a dumper and is converted into thermal energy.

In the case of an SPF (Spectrum Purity Filter) which uses a reflectivetype diffraction lattice, it is necessary to provide blazed grooves inorder to enhance the efficiency of diffraction of EUV radiation.However, since it is necessary to form extremely minute grooves whoseheights are several tens of nanometers at a pitch of a few μm in orderto eliminate aberration of the resulting diffracted EUV radiation,accordingly curved grooves are required whose pitch changes (refer toNon-Patent Reference #1).

Thus, as described in a fourth prior art document (refer to PatentReference #4), it is proposed to create a reflective type SPF byprocessing an Mo/Si multi layer which has been coated onto the frontsurface of a mirror into the shapes of blazed grooves.

-   Patent Reference #1: Japanese Laid-Open Patent Publication    2005-64135.-   Patent Reference #2: Japanese Laid-Open Patent Publication    2006-80255.-   Patent Reference #3: U.S. Pat. No. 6,469,827.-   Patent Reference #4: U.S. Pat. No. 7,050,237.-   Non-Patent Reference #1: “EUV spectral purity filter: optical and    mechanical design, grating fabrication, and testing”, H. Kierey et    al., “Advances in Mirror Technology for X-Ray, EUV-Lithography,    Laser and Other Applications”, edited by Ali M. Khounsary, Udo    Dinnger, and Kazuya Ohta, Proceedings of SPIE, Vol. 5193.

SUMMARY OF THE INVENTION

The second problem is that, with the prior art technique described abovein which the multi layer is subjected to blazing processing, it isnecessary to superimpose a total of 2000 or more of the Mo/Si multilayers. This is because, in order reliably to separate the radiationinto diffracted EUV radiation and regularly reflected radiation of otherwavelengths, the blaze angle must be set to be large. And, in order tomake the blaze angle large in this manner, it becomes necessary toprovide 2000 or more multi layers.

Moreover, if a thin layer film type SPF is used, the transmissionefficiency for EUV radiation is decreased, since the transmittivity forEUV radiation is low. Moreover, in the case of such a thin layer filmtype SPF, there is a possibility of deformation or damage due to theabsorption of infrared radiation and the like, and accordingly thereliability and the convenience of use are low.

The present invention has been conceived in view of the problemsdescribed above, and an objective thereof is to provide a semiconductorexposure device, which can irradiate extreme ultra violet radiation ofhigh purity upon a mask. Another objective of the present invention isto provide such a semiconductor exposure device, which, by using amirror which is made by laminating together a plurality of regions inwhich the numbers and shapes of the multi layers are different, makes itpossible to enhance the purity of the extreme ultra violet radiation byutilizing beneficial diffraction effects of several types. Yet furtherobjectives of the present invention will become clear from thesubsequent description of certain embodiments thereof.

In order to solve the problems described above, a semiconductor exposuredevice according to a first aspect of the present invention includes anillumination optical system which utilizes extreme ultra violetradiation, and: the illumination optical system includes a plurality ofmirrors for extreme ultra violet radiation which reflect the extremeultra violet radiation, and at least one of the mirrors for extremeultra violet radiation separates extreme ultra violet radiation fromradiation of other wavelengths, and includes: a substrate portion; afoundation portion formed from a first multi layer which is provided onone side of the substrate portion; and a reflecting portion made byforming grooves of predetermined shapes in a second multi layer which isintegrally provided on the other side of the first multi layer from thesubstrate portion.

The one mirror for extreme ultra violet radiation may be formed ashaving a concave surface which reflects incident extreme ultra violetradiation as almost parallel radiation.

Or, the one mirror for extreme ultra violet radiation may be formed ashaving a planar surface which reflects incident extreme ultra violetradiation.

The illumination optical system may include an intermediate focus pointat which the extreme ultra violet radiation is focused, and a radiationshield member, having an aperture portion which allows the passage ofthe extreme ultra violet radiation, may be provided in the neighborhoodof the intermediate focus point.

The first multi layer and the second multi layer may be formedintegrally from a plurality of pair layers, with the thickness dimensionof the plurality of pair layers which constitute each of the first multilayer and the second multi layer being set according to the angle atwhich extreme ultra violet radiation is incident thereupon.

The grooves of predetermined shape may be made as blazed grooves. Or,the grooves of predetermined shape may be made as triangular roof-likegrooves. Or, the grooves of predetermined shape may be made asundulating wave-like grooves.

And the grooves of predetermined shape may be provided as concentriccircles or parallel lines.

The total number of pair layers which constitute the combination of thefirst multi layer and the second multi layer may be in the range from100 to 1000.

And a semiconductor exposure device according to a second aspect of thepresent invention includes an illumination optical system which utilizesextreme ultra violet radiation, and also includes: a chamber connectedto the output side of a light source device which outputs extreme ultraviolet radiation; a first mirror which reflects extreme ultra violetradiation incident from the light source device as parallel radiation; asecond mirror upon which the extreme ultra violet radiation reflected bythe first mirror is incident, and which makes the intensity of theextreme ultra violet radiation uniform; a third mirror which condensesthe extreme ultra violet radiation whose intensity has been madeuniform, and irradiates it upon a mask; and a radiation shield member,provided at a position between the second mirror and the third mirror,or at a position between the first mirror and the second mirror, andwhich absorbs or attenuates radiation of other wavelengths than theextreme ultra violet radiation; with the first mirror including: asubstrate portion; a foundation portion formed from a first multi layerwhich is provided on one side of the substrate portion; and a reflectingportion made by forming grooves of predetermined shapes in a secondmulti layer which is integrally provided on the other side of the firstmulti layer from the substrate portion.

The first mirror may be provided so that the angle of incidencethereupon of the extreme ultra violet radiation is in the range from 0°to 30°, or in the range from 60° to 80°.

The radiation shield member may be built as a pinhole member whichallows the passage only of the extreme ultra violet radiation, whileabsorbing or attenuating the radiation of other wavelengths.

The radiation shield member may be built as a dumper member whichabsorbs the radiation of other wavelengths.

Moreover, a semiconductor exposure device according to a third aspect ofthe present invention includes an illumination optical system whichutilizes extreme ultra violet radiation, and also includes: a chamberconnected to the output side of a light source device which outputsextreme ultra violet radiation; a first mirror which reflects extremeultra violet radiation incident from the light source device as parallelradiation; a second mirror upon which the extreme ultra violet radiationreflected by the first mirror is incident, and which makes the intensityof the extreme ultra violet radiation uniform; a third mirror whichcondenses the extreme ultra violet radiation whose intensity has beenmade uniform, and irradiates it upon a mask; a fourth mirror which isprovided between the output side of the light source device and thefirst mirror, and which reflects extreme ultra violet radiation incidentfrom the light source device towards the first mirror, and a radiationshield member, provided at a position between the second mirror and thethird mirror, which absorbs or attenuates radiation of other wavelengthsthan the extreme ultra violet radiation; and the fourth mirror includes:a substrate portion; a foundation portion formed from a first multilayer which is provided on one side of the substrate portion; and areflecting portion made by forming grooves of predetermined shapes in asecond multi layer which is integrally provided on the other side of thefirst multi layer from the substrate portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory figure showing the overall structure of an EUVexposure system;

FIG. 2 is an explanatory figure showing an EUV light source device;

FIG. 3 is an explanatory figure showing the structure of an exposuredevice;

FIG. 4 is a sectional view showing a magnified view of blazed grooves ona mirror;

FIG. 5 is a plan view showing these blazed grooves on the mirror;

FIG. 6 is an explanatory figure showing the directions of these blazedgrooves on the mirror in magnified view;

FIG. 7 is a characteristic figure for the setting of Mo/Si pair layerthickness according to the angle of incidence;

FIG. 8 is a characteristic figure showing the relationship between theangle of incidence of EUV radiation and reflectivity;

FIG. 9 is an explanatory figure showing the relationship between anoptical system for making the intensity of EUV radiation uniform and apinhole array;

FIG. 10 is an explanatory figure showing the operation of the pinholearray;

FIG. 11 is an explanatory figure showing an exposure device according toa second embodiment;

FIG. 12 is a sectional view showing a magnified view of the directionsof blazed grooves on a mirror;

FIG. 13 is a plan view showing the blazed grooves on the mirror;

FIG. 14 is an explanatory figure showing an exposure device according toa third embodiment;

FIG. 15 is an explanatory figure showing an exposure device according toa fourth embodiment;

FIG. 16 is an explanatory figure showing a method of manufacturing amirror according to a fifth embodiment;

FIG. 17 is an explanatory figure showing a method of manufacturing amirror according to a sixth embodiment;

FIG. 18 is an explanatory figure showing a method of manufacturing amirror according to a seventh embodiment;

FIG. 19 is an explanatory figure showing a magnified view of a mirroraccording to an eighth embodiment;

FIG. 20 is a sectional view showing a magnified view of a mirroraccording to a ninth embodiment;

FIG. 21 is an explanatory figure showing an exposure deviceincorporating a mirror according to a tenth embodiment; and

FIG. 22 is an explanatory figure showing an exposure deviceincorporating a mirror according to a eleventh embodiment.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

In the following, various embodiments of the present invention will bedescribed in detail with reference to the drawings. In theseembodiments, as an example, an exposure system 1 which utilizes EUVradiation will be explained. And, as will be explained hereinafter, inthese embodiments, a mirror 510 which is included in an illuminationoptical system 500 of an exposure device 3 will be shown as an exampleof a mirror which reflects EUV radiation. In these embodiments, areflective type diffraction lattice is integrally provided in thismirror 510 within this illumination optical system. Due to this, thismirror 510 is simultaneously endowed with its basic function and with afunction of serving as a SPF. The basic function of this mirror 510 isto reflect EUV radiation which is incident thereon as parallel rays. Inthese embodiments, by providing grooves of predetermined shapes in themulti layers upon the collector mirror 510, it is possible to utilizethree types of diffraction operation: Bragg reflection by the multilayers of the foundation portion and by the multi layers of the portionin which the grooves of predetermined shape are provided; diffractiondue to the repeated pattern of the multi layers which emerges at thefront surfaces of the grooves of predetermined shape; and diffractiondue to the grooves of predetermined shape themselves. In theseembodiments, as examples of these grooves of predetermined shapes,grooves shaped as blazed, triangular roof-like grooves, and undulatingwave-like grooves will be explained.

Embodiment 1

A first embodiment will now be explained with reference to FIGS. 1through 10. FIG. 1 is an explanatory figure, schematically showing theoverall structure of an EUV exposure system 1. This exposure system 1,for example, comprises an EUV light source device 2 and an exposuredevice 3.

The details of the EUV light source device 2 will be described in moredetail subsequently, but now a first summary will be given. The EUVlight source device 2 is a device which generates EUV radiation andsupplies it to the exposure device 3. A target supply device 120supplies a target 200 made from tin or the like into a vacuum chamber100. A driver laser light source 110 irradiates a driver laser upon thetarget 200 and converts it into plasma 201. The EUV radiation which isgenerated from this plasma 201 is collected by an EUV collector mirror130 and is conducted towards the exposure device 3.

The exposure device 3 comprises, for example, an illumination opticalsystem 500, a mask 600, and a projection optical system 700. Theillumination optical system 500 is an optical system for causing the EUVradiation supplied from the EUV light source device 2 to be incidentupon the mask 600, and comprises a plurality of mirrors. A circuitpattern is formed upon the mask 600. The projection optical system 700is an optical system for creating a circuit pattern by conducting EUVradiation which has been reflected by the mask 600 so that it isincident upon a semiconductor wafer.

As shown in magnified view at the lower portion of FIG. 1, in thisembodiment, upon at least one mirror 510 among the plurality of mirrorswhich are incorporated in the illumination optical system 500, there areintegrally formed a flat foundation portion 512, and a reflectingportion 513 which is formed with grooves of predetermined shapes. Thismirror 510 is built so that the direction of the EUV radiation 204 whichis reflected is different from the directions of rays of reflectedradiation 301A and 301B which are radiation other than EUV radiation(sometimes herein this other type of radiation is generally referred toby the reference symbol 301). Due to this, the reflected EUV radiation204 is separated from the reflected radiation 301A and 301B which is notEUV radiation, so that it is arranged for only the EUV radiation to beemitted towards the mask 600.

The structure of the EUV light source device 2 will now be explainedwith reference to FIG. 2. As will be described hereinafter, this EUVlight source device 2, for example, comprises a vacuum chamber 100, adriver laser light source 110, a target supply device 120, the EUVcollector mirror 130, coils for magnetic field generation 140 and 141,an aperture member 160, vacuum exhaust pumps 170 and 171, and a gatevalve 180.

The vacuum chamber 100 is made by connected together a first chamber 101whose volume is relatively large, and a second chamber 102 whose volumeis relatively small. The first chamber 101 is a main chamber in whichgeneration of plasma and so on is performed. And the second chamber 102is a connection chamber, and is for supplying the EUV radiation emittedfrom the plasma to the exposure device.

The first vacuum exhaust pump 170 is connected to the first chamber 101,and the second vacuum exhaust pump 171 is connected to the secondchamber 102. Due to this, each of these chambers 101 and 102 ismaintained in a vacuum state. It would be acceptable to constitute eachof these vacuum exhaust pumps 170 and 171 as a separate pump, oralternatively to constitute them as one single combined pump.

The target supply device 120 supplies targets 200 as droplets of solidor liquid by, for example, applying heat to a material such as tin (Sn)or the like and melting it. It should be understood that while, in thisexplanation of the first embodiment, tin is suggested as an example of atarget substance, this is not limitative of the present invention; itwould also be acceptable to utilize some other substance, such as, forexample, lithium (Li) or the like. Or, it would also be acceptable toprovide a structure in which targets are supplied in any one of thegaseous, liquid, or solid state, using a material such as argon (Ar),xenon (Xe), krypton (Kr), water, alcohol, or the like. Furthermore, itwould also be acceptable to supply targets consisting of liquid orfrozen droplets of stannane (SnH₄), tin tetrachloride (SnCl₄), or thelike.

The driver laser light source 110 outputs laser pulses for exciting thetargets 200 which are supplied from the target supply device 120. Thisdriver laser light source 110 may, for example, consist of a CO₂ (carbondioxide gas) pulse laser light source. The driver laser light source 110may, for example, emit laser radiation with the specification of:wavelength 10.6 μm, output 20 kW, pulse repetition frequency 100 khZ,and pulse width 20 nsec. It should be understood that, while a CO₂ pulselaser is suggested here as an example of a laser light source, thisshould not be considered as being limitative of the present invention.

The laser radiation for excitement which is outputted from the driverlaser light source 110 is incident into the first chamber 101 via thecollector lens 111 and the incidence window 112. This laser radiationwhich is incident into the first chamber 101 irradiates a target 200which is supplied from the target supply device 120, via an incidenceaperture 132 which is provided to the EUV collector mirror 130.

When the laser radiation irradiates the target, a target plasma 201 isgenerated. In the following, for convenience, this will simply be termedthe “plasma 201”. This plasma 201 emits EUV radiation 202 centeredaround the wavelength of 13.5 nm. This EUV radiation 202 which has beenemitted from the plasma 201 is incident upon the EUV collector mirror130, and is reflected thereby. The reflected radiation 203 is focused atan intermediate focus point (IF: Intermediate Focus) which is a focalpoint. And this EUV radiation which has thus been focused at the focuspoint IF is conducted to the exposure device via the gate valve 180,which is in its opened state.

The aperture member 160 is provided in the neighborhood of the focuspoint IF, so as to separate between the first chamber 101 and the secondchamber 102. This aperture member 160 may, for example, be made as aplate shaped member which is provided with a small aperture. The body ofthis aperture member 160 absorbs radiation other than EUV radiation(such as DUV, UV, VIS (visible light), and IR) and converts it to heat.Due to this aperture member 160, the penetration of radiation other thanEUV radiation, and of debris, to the side of the exposure device 3 isprevented as much as possible.

A pair of coils 140 and 141 for magnetic field generation are providedabove and below the optical path which the EUV radiation 202 and 203pursues from the plasma 201 via the EUV collector mirror 130 towards thefocus point IF. The axes of these two coils 140 and 141 coincide. Eachof the coils 140 and 141, for example, may consist of an electromagnetwhich has a superconducting coil. When electrical currents flow in thesame direction in both of the coils 140 and 141, a magnetic field isgenerated. This magnetic field has high magnetic flux density in theneighborhoods of the coils 140 and 141, and has a lower magnetic fluxdensity at points intermediate between the coils 140 and 141.

When the laser radiation is irradiated upon the target, debris iscreated. Debris which carries electric charge (ions such as plasma andso on) is captured by the magnetic field generated by the coils 140 and141, and moves downward in FIG. 1 while executing helical motion due toLorentz force. This debris which has moved downwards is sucked out bythe first vacuum exhaust pump 170 and is exhausted to the exterior ofthe first chamber 101. The position at which the magnetic fieldgeneration device (in this embodiment, the coils 140 and 141) isinstalled should be a position at which the ionized debris can bedischarged by the magnetic flux generated by the device, while avoidingthe various optical components of the system. Accordingly, theconfiguration shown in the figure should not be considered as beinglimitative of the present invention.

It would also be acceptable to arrange for the magnetic flux density ofone or the other of the coils 140 and 141 to be relatively weaker, sothat the debris which carries electrical charge flows towards that onethereof where the magnetic flux density is the lower.

For convenience, explanation of the power supply device and the wiringwhich supply electrical current to the coils 140 and 141, and of themechanisms for cooling the aperture member 160 and the EUV collectormirror 130 and so on, will herein be omitted, and moreover theseelements are not shown in the figures. However, without undueexperimentation, a person of ordinary skill in the art will be able todesign a suitable such power supply construction and a suitable suchcooling construction based upon the disclosure in this specification,and will also be able actually to manufacture them.

A high vacuum state is maintained within the first chamber 101 by thefirst vacuum exhaust pump 170, and a vacuum state is maintained withinthe second chamber 102 by the second vacuum exhaust pump 171. Thepressure within the first chamber 101 is set to be lower than thepressure within the second chamber 102. Moreover, the ions (i.e. theelectrified debris particles) within the first chamber 101 are capturedby the magnetic field which is generated by the coils 140 and 141.

Accordingly, it is possible to prevent any of the debris which iscreated within the first chamber 101 from getting into the secondchamber 102. Moreover, even if some debris or the like should get intothe second chamber 102, nevertheless, due to the operation of the secondvacuum exhaust pump 171, it is possible to extract this debris or thelike to the exterior of the second chamber 102. Because of thisstructure, it is possible effectively to prevent any debris or the likefrom getting into the exposure device.

Thus, in this embodiment, the magnetic field which is created by thecoils 140 and 141 is utilized as a protection means for protecting thevarious optical elements from debris. These various optical elementsinclude the EUV collector mirror 130, the incidence window 112,incidence windows for optical sensors of various types (not particularlyshown) which are provided for observing phenomena within the vacuumchamber 100, and so on.

Since the ions in the debris which is emitted from the plasma 201 areelectrically charged, they are captured by the magnetic field and aredischarged by the first vacuum exhaust pump 170. However, neutral debriswhich is not electrically charged is not constrained by the magneticfield.

Accordingly, if no particular countermeasures were to be instituted,this neutral debris gradually contaminates the various optical elementswithin the vacuum chamber 100 and damages them. Moreover, if and whensuch neutral debris within the first chamber 101 gets into the exposuredevice via the second chamber 102, it may also even contaminate thevarious optical elements within the exposure device.

By contrast, in this embodiment, the construction is such that thevacuum chamber 100 is subdivided into the first chamber 101 whose volumeis relatively greater and the second chamber 102 whose volume isrelatively smaller, and moreover the pressure within the first chamber101 is set to be lower than the pressure within the second chamber 102.Furthermore, the aperture member 160 is provided so as to separatebetween the first chamber 101 and the second chamber 102, so that, inaddition to limiting spatial migration from the first chamber 101 andthe second chamber 102, the probability of neutral debris getting intothe second chamber 102 from the first chamber 101 is reduced. Even ifneutral debris should get into the second chamber 102, this debris willbe discharged to the exterior by the second vacuum exhaust pump 171.Accordingly, in this embodiment, it is possible to prevent debris withinthe EUV light source device 2 from getting into the exposure device,before it even happens.

Although it is possible to prevent the exposure device from beingcontaminated by debris, neutral debris gradually diffuses and piles upwithin the vacuum chamber 100. Accordingly, depending upon the timeperiod which elapses, there is a possibility that the front surface 131of the EUV collector mirror 130 may gradually become contaminated bydebris. In this case, maintenance work should be performed.

In such maintenance work, for example, the operation of the EUV lightsource device 1 is stopped, the gate valve 180 is closed so as perfectlyto intercept communication between the exposure device and the vacuumchamber 100, and the EUV collector mirror 130 is cleaned with an etchantgas.

For example, hydrogen gas, a halogen gas, a hydrogenated halogen gas,argon gas, or a mixture thereof may be used as the etchant gas. The EUVcollector mirror 130 could also be heated by a heat application devicenot shown in the figures, in order to promote the cleaning thereof.Moreover, it might also be arranged to excite the etchant gas with RF(Radio Frequency) radiation or with microwaves, in order to promote thecleaning.

When the cleaning has been completed, the supply of the etchant gas tothe vacuum chamber 100 is stopped, and, after a sufficient level ofvacuum has been established by the vacuum exhaust pumps 170 and 171, thegate valve 180 is opened, and the operation of the EUV light sourcedevice 2 is resumed.

FIG. 3 is an explanatory figure showing the structure of the exposuredevice 3. The following explanation will focus upon the illuminationoptical system 500. The illumination optical system 500, the mask 600,and the projection optical system 700 are provided within a chamber 400of the exposure device 3. As explained with reference to FIG. 2, thechamber 100 of the EUV light source device 2 is connected to the chamber400 via the gate valve 180.

The illumination optical system 500, for example, may include acollimator mirror 510, a fly-eye mirror array 520, a pinhole array 530,and a condenser mirror 540. This collimator mirror 510 is a mirror forreflecting EUV radiation 203 which is incident thereon from the EUVlight source device 2 as parallel radiation. In some cases, thecondenser mirror 130 within the EUV light source device 2 is termed the“C1 mirror”, while the collimator mirror 510 within the illuminationoptical system 500 is termed the “C2 mirror”.

As well as including the EUV radiation 203, the radiation which isincident from the EUV light source device 2 also includes radiation ofother wavelengths. As described above, this radiation of otherwavelengths is made up of DUV, UV, VIS, and IR. Moreover, since the CO₂laser radiation for exciting the target is scattered and reflected bythe target, some of this CO₂ laser radiation is also incident from theEUV light source device 2. Since, as will be described hereinafter, thecollimator mirror 510 possesses the structure which is characteristic ofthe present invention, the direction in which the EUV radiation 204 isreflected is different from the directions 304 in which the radiation301 other than the EUV radiation is reflected.

The fly-eye mirror array 520 is a mirror array in which a plurality ofconcave surface mirrors 521 are arranged upon a plane (refer to FIG. 9).This fly-eye mirror array 520 functions as a beam homogenizer. In otherwords, the fly-eye mirror array 520 makes the intensity of the EUVradiation uniform, and is arranged so as to direct this resultinguniform EUV radiation in a direction to be incident upon the mask 600.

After having been temporarily gathered to a number of focal points bythe concave surface mirrors 521 in the fly-eye mirror array 520, the EUVradiation 205 which has been reflected by these concave surface mirrors521 is then diffused. Thus, in this embodiment, a pinhole array 530 isprovided in the neighborhood of the group of focal points of the fly-eyemirror array 520. This group of focal points of the fly-eye mirror array520 is the set of the focal points of the various concave surfacemirrors 521 in the fly-eye mirror array 520. The pinhole array 530 isprovided with small apertures which correspond to these focal points ofthe concave surface mirrors 521.

The condenser mirror 540 is a mirror for reflecting the EUV radiation205 which is incident from the fly-eye mirror array 520 via the pinholearray 530 towards the mask 600. The EUV radiation 207 which is reflectedby the mask 600 proceeds towards the projection optical system 700.

Next, the collimator mirror 510 will be explained with reference toFIGS. 4 through 6. FIG. 6 is an explanatory figure which schematicallyshows a cross section of the collimator mirror 510. A multi layer whichselectively reflects radiation at a predetermined wavelength is formedupon the front surface of the collimator mirror 510. In this embodiment,this predetermined wavelength is 13.5 nm. This multi layer is made bylaminating together a large number of pair layers made from molybdenumand silicon (Mo/Si). Moreover, a large number of blazed grooves 513 areformed upon this multi layer which covers the front surface of themirror 510.

As shown in the enlarged cross sections of FIGS. 5 and 6, the blazedgrooves 513 of this embodiment are formed as parallel straight lines. Itshould be understood that the shapes of the blazed grooves 513 are notlimited to those shown in FIG. 6. As shown in further embodiments whichwill be described hereinafter, the blazed grooves 513 may be formed invarious shapes. Moreover, in this first embodiment, the blazed grooves513 are formed so that their abrupt step portions face towards thecenter of the mirror (its central axis), i.e. away from the outer edgeof the mirror, while their gently sloping portions face towards theouter edge of the mirror.

FIG. 4 is a sectional view showing a portion of the EUV collector mirrorin magnified form. In FIG. 3, the axial line AX1 is an axis which isperpendicular to the substrate portion 511 of the collimator mirror 510,while the other axial line AX2 is an axis which is perpendicular to thesloping surface of one of the blazed grooves 513.

The substrate portion 511 of the collimator mirror 510 is made from amaterial such as, for example, silicon or silicon carbide (SiC) ornickel alloy or the like whose thermal conductivity is good. Apredetermined number of multi layers (Mo/Si pair layers) are coated uponthe front surface of the substrate portion 511 (which is its uppersurface in FIG. 4, and corresponds to “a surface” in the Claims).

In this embodiment, the number of Mo/Si pair layers which are coatedupon the substrate portion 511 is in the range from 100 to 1000. Anddesirably, in this embodiment, around 300 of these Mo/Si pair layersshould be laid over one another upon the front surface of the substrateportion 511. Each of these Mo/Si pair layers is a pair layer whichconsists of one molybdenum layer and one silicon layer, and the multilayer is made by laminating together a large number of such Mo/Si pairlayers.

The blazed grooves 513 are processed (to a depth H) into around 250 ofthe 300 pair layers of the multi layer upon the mirror front surface(whose total thickness is HO), while the approximately 50 layers at thebottom, which constitute a composite sub-layer) are left just as theyare. The approximately 50 pair layers (the composite sub-layer ofthickness ΔH) at the bottom of the multi layer correspond to the “firstmulti layer” of the Claims. A foundation portion 512 is formed from thiscomposite sub-layer of thickness ΔH. In order to cause the EUV radiationto be reflected by this foundation portion 512 by Bragg reflection, thisfoundation portion 512 should consist of from around 40 to around 60 ofthe Mo/Si pair layers. The composite sub-layer (of thickness H)consisting of around 250 pair layers which is positioned over thefoundation portion 134, and in which the blazed grooves 513 are formed,corresponds to the “second multi layer” of the Claims, while the blazedgrooves 513 correspond to the “reflecting portion” of the Claims.

It should be understood that the various numerical values given abovefor numbers of pair layers (sub-layer thicknesses) of 300, 250, and 50,are only cited by way of example for convenience of explanation; thepresent invention should not be considered as being limited to thesenumerical values. Finally, the number of the pair layers may be anyvalue within the range from 100 to 1000, provided that the foundationportion 512 and the reflecting portion are able to manifest the functionof reflecting the EUV radiation by Bragg reflection and also thefunction of regularly reflecting the radiation other than EUV radiationin other directions, while the blazed grooves 133 are able to manifestboth the function of diffracting the EUV radiation due to the exposedpatterns of the pair layers on the reflecting portions, i.e. on thefront surfaces of the blazed grooves, and also the function ofdiffracting the EUV radiation due to the patterns of the blazed groovesthemselves.

If the number of the pair layers is less than 100, then it is notpossible to obtain the required blaze angle θB, so that sometimes it maybe the case that it is not possible sufficiently to separate the EUVradiation from the radiation of other wavelengths. By contrast, if thenumber of the pair layers is greater than 1000, then a great deal oflabor must be utilized during fabrication of the mirror, and moreoverthe internal stress is increased, so that there is a possibility thatthe multi layer may become detached.

Thus, in this embodiment, as one example of a value between 100 and1000, the value of 300 is selected for the number of pair layers, andthe above described reflective type diffraction lattice made from thisnumber of pair layers is provided integrally upon the collimator mirror510. The more multi layers are provided as stacked over one another, thegreater is it possible to make the blaze angle θB, so that it ispossible to separate the EUV reflected radiation 204 and the radiation301A and 301B of other wavelengths, in a simple and easy manner.

In this embodiment, it is possible to set the number of Mo/Si pairlayers which are laminated together to any value in the range from 100to 1000, and it is possible to reduce the stress set up in the multilayer, and thus to prevent detachment of the multi layer. Moreover, withregard to the efficiency of reflection of EUV radiation, it is possibleto keep the performance around 60% to 70%, which is similar to that ofthe prior art.

In other words, since the collimator mirror 510 of this first embodimentof the present invention is endowed, not only with its basic function ofreflecting EUV radiation into parallel radiation at a reflectivity ofaround 60% to 70%, but also with the function of acting as a SPF,accordingly the loss of the EUV radiation due to this single reflectionis held down to around 30%, which is the same is in the prior art, andmoreover the purity of the EUV radiation is enhanced.

It should be understood that it would also be acceptable, after thefrontmost surface of the mirror has been processed in order to producethe blazed grooves 513, to coat it with ruthenium (Ru) or the like sothat the exposed portion of the Mo/Si layer which has been processeddoes not become oxidized; and this results in a structure with whichdecrease of the diffraction efficiency for the EUV radiation isprevented. Moreover, as will be explained hereinafter with reference toFIG. 7, it is desirable for the thicknesses of the Mo/Si pair layers tobe set according to the angle of incidence of the EUV radiation.

If the angle of incidence of the EUV radiation 203 which is incidentfrom the plasma 201 upon the collimator mirror 510 shown in FIG. 4 istermed α, then the EUV radiation 204 is reflected at almost the angle α,to be incident upon the fly-eye mirror array 520 (refer to FIG. 3). Bycontrast, the DUV, UV, VIS, and IR radiation components (301) such asthe CO₂ laser radiation are regularly reflected at an angle α+2θβ(302A). Accordingly, at the position of the pinhole array 530 (refer toFIG. 3), the EUV reflected radiation 204 and the regularly reflectedradiation such as the CO₂ radiation 302A and so on are separated out.

In other words, due to the blazed grooves 513 (whose blaze angle is θB),with the exception of the EUV radiation 203, the DUV, UV, VIS, and IRare regularly reflected (302A) at the angle of α+2θB by the surfaceswhich are at the angle θB. Accordingly, it is possible to separate theEUV radiation 204 which is reflected or diffracted at almost the angle αand the other radiation (DUV, UV, VIS, and IR). Additionally, thecollimator mirror 510 fulfils the function of an SPF. As will bedescribed hereinafter, the other radiation 302A which proceeds indirections other than that of the EUV radiation 204 is absorbed by thewall portion of the pinhole array 530 (refer to FIG. 3).

Furthermore, IR radiation such as the CO₂ laser radiation is diffracted(302B) at an angle of α+θd (or α−θd; not shown in the drawing) by theblazed grooves 513. Since, in this embodiment, the wavelength of thelaser radiation is 10.6 μm, and accordingly the angle θd in FIG. 4 is27.6 mrad. In other words, only the EUV radiation 204 is diffracted byjust the angle of 27.6 mrad (302B). This diffracted radiation (302B) isalso absorbed by the wall portion of the pinhole array 530 (refer toFIG. 3).

Although for the sake of convenience this feature is not shown in thefigure, the DUV, UV, and VIS (301) which are incident upon the mirror510 are diffracted by the gratings which are formed by the periodicstripe patterns of the alternating molybdenum and silicon layersappearing upon the sloping surfaces of the blazed grooves 513 (in thisembodiment, these stripe patterns have pitch of 1.54 μm), and followpaths at angles which are different from that of the EUV radiation 204.This diffracted radiation is also absorbed by the wall portion of thepinhole array 530 (refer to FIG. 3). The radiation which, as describedabove, proceeds after being separated by the mirror 510 at angles whichare different from that of the EUV radiation (i.e. the radiationcomponents designated above as 301A and 302B, and the radiation which isdiffracted by the periodic stripe patterns of molybdenum and siliconwhich appear upon the sloping surfaces of the blazed grooves 513) are,as a general term, termed the radiation 302 other than EUV radiation.

FIG. 7 shows a characteristic for setting the thickness of the Mo/Sipair layers according to the angle of incidence (α) of the EUV radiationupon the collimator mirror 510. As shown in FIG. 7, as the angle ofincidence increases from 0° to 50°, the thickness of the pair layersincreases from around 6 nm to around 10 nm. When the angle of incidenceα is 12°, the thickness of the pair layers is 6.9 nm. From the generalvicinity where the angle of incidence exceeds 50°, the rate of increaseof the thickness of the pair layers becomes great. When the angle ofincidence is around 70°, the thickness of the pair layers becomes around20 nm. It should be understood that the characteristic shown in FIG. 7is only given by way of example; the present invention is not to beconsidered as being limited to the characteristic shown in FIG. 7.

FIG. 8 is a graph showing a relationship between the angle of incidenceof the EUV radiation 203 and the reflectivity. In FIG. 8, thereflectivity is shown along the vertical axis, while the angle ofincidence is shown along the horizontal axis.

In the range of angle of incidence from 0° (perpendicular to the mirror510) to 20°, the reflectivity gently decreases according to the angle ofincidence, from around 75% to around 70%. In the range of angle ofincidence from 20° to 30°, the reflectivity decreases according to theangle of incidence from around 70% to around 55%. Moreover, in the rangeof angle of incidence from 30° to 45°, the reflectivity decreases ratherabruptly according to the angle of incidence, from around 55% to around40%. And, in the range of angle of incidence from 45° to 60°, thereflectivity increases quite steeply according to the angle ofincidence, from around 40% to around 60%. Although only angles ofincidence up to 70° are shown in FIG. 8, in the range of angle ofincidence from 60° to 80°, the reflectivity gently increases from around60% to around 65%.

Thus, in this embodiment, the angle of the mirror 510 is set so that theangle of incidence of the EUV radiation is in the range from 0° to 30°,or in the range from 60° to 80°. It should be understood that, if theangle of incidence is greater than 80°, then it is not possible for theoperation of the present invention for separation of the EUV radiation203 from the other radiation 301 to take place, because the EUVradiation does not enter into the pair layers.

Since the collimator mirror 510 of this embodiment includes thefoundation portion 512 and the blazed grooves 513, both of which aremade from a multiple Mo/Si pair layers, accordingly it is capable ofproviding a plurality of different diffraction operations.

FIG. 9 is an explanatory figure showing the beam homogenizer functionperformed by the fly-eye mirror array 520, and the operation of thepinhole array 530. The EUV radiation 204 and the other radiation 302which are reflected by the mirror 510 are both incident upon each of theconcave surface mirrors 521 included in the fly-eye mirror array 520.

The radiation 205(1) and 205(2) which has been reflected by theseconcave surface mirrors 521, after having been gathered together atintermediate focal points, is then incident upon the condenser mirror540, and is supplied to the mask 600. In other words, the radiation205(1) and 205(2) which is reflected by the concave surface mirrors 521is reflected by the condenser mirror 540 (as the radiation 206(1) and206(2)), and then is illuminated upon the front surface of the mask 600.Due to this, it is possible to make the intensity of the EUV radiationwhich is incident upon the mask 600 uniform.

In FIG. 9, the EUV radiation 204(1) is EUV radiation which is incidentupon a concave surface mirror 521 on the right side, while the EUVradiation 204(2) is EUV radiation which is incident upon a concavesurface mirror 521 on the left side. In a similar manner, the referencesymbol 302(1) is appended to the other radiation which is incident uponthis concave surface mirror 521 on the right side, while the referencesymbol 302(2) is appended to the other radiation which is incident uponthe concave surface mirror 521 on the left side. For convenience,radiation incident upon the concave surface mirrors 521 in the center isnot shown in the figure.

And the pinhole array 530 is disposed at the position of the group offocus points at which the concave surface mirrors 521 of the fly-eyemirror array 520 are focused. As shown in the enlarged view of FIG. 10,the positions of the focus points F(521) of the concave surface mirrors521 and of the pinholes 531 coincide with one another. The EUV radiation205 which arrives from the concave surface mirrors 521 passes throughthe pinholes 531, while the radiation 302 other than the EUV radiationis intercepted by the wall portion of the pinhole array 530. In otherwords, it is possible to ensure than only the EUV radiation 204 whosedirection has been separated out by the mirror 510 is allowed to beincident upon the condenser mirror 540, while the radiation 301 otherthan the EUV radiation can be intercepted by the wall portions of thepinhole array 530 and is converted to heat. This is accomplished by thecollimator mirror 510 being endowed with the additional function ofacting as an SPF.

With this embodiment which has the structure described above, since theblazed grooves 513 are formed by processing the sub-layer of thecollimator mirror 510 which is made by superimposing a predeterminednumber of Mo/Si pair layers, accordingly not only can the collimatormirror 510 be endowed with its basic function of reflecting the EUVradiation, but also with the function of acting as an SPF whichseparates the EUV radiation from the radiation of other wavelengths.Furthermore, in this embodiment, since the pinhole array 530 is providedbetween the fly-eye mirror array 520 and the condenser mirror 540,accordingly it is possible to supply only the EUV radiation to the mask600. Due to this, in this embodiment, it is possible to supply a greaterproportion of the EUV radiation to the mask 600, as compared to the casein which a separate reflective type diffraction lattice is used, andmoreover it is possible to reduce the number of components in theexposure device 3, thus keeping its manufacturing cost low.

In this embodiment, the blazed grooves 513 are formed by laminating anumber of Mo/Si pair layers in the range of 100 to 1000 upon thesubstrate portion 511. Accordingly, as compared with a prior arttechnique in which 2000 or more Mo/Si pair layers were superimposed, thestress in the multi layer is reduced, so that there is no fear that themulti layer may become detached due to such stress, and accordingly thereliability and the convenience of use are enhanced. Moreover, since thenumber of layers is reduced, accordingly the manufacturing cost of thiscollimator mirror 510 can also be reduced.

Since, in this embodiment, the collimator mirror 510 is endowed with thefunction of a SPF, accordingly it is possible to provide the exposuredevice with EUV radiation of high purity which has been subjected toonly a single reflection. Therefore a higher efficiency can be obtainedthan in the case of the prior art, in which the EUV radiation wasreflected a plurality of times.

Moreover, since the collimator mirror 510 of this first embodiment isutilized in the illumination optical system 500 of the exposure device3, accordingly it does not experience any influence due to debris.Therefore, even when a mirror of a special type of construction such asthat shown in FIG. 4 is employed, it can still be used over the longterm.

Embodiment 2

A second embodiment of the present invention will now be explained onthe basis of FIGS. 11 through 13. The various embodiments of the presentinvention which are described below correspond to variants of the firstembodiment described above. Accordingly, the explanation thereof willfocus upon the aspects in which these embodiments differ from the firstembodiment. The aspects of difference between this second embodiment andthe first embodiment are that the blazed grooves are formed asconcentric circles, that the blazed grooves are formed so that theirabrupt step portions face away from the center of the mirror (itscentral axis) towards the outer edge of the mirror and their gentlysloping portions face towards the central axis of the mirror, i.e. sothat the blazed grooves are angled in the opposite direction to those ofthe first embodiment described above, and that, along with this point ofdifference, a dumper 560 is additionally provided.

FIG. 11 is an explanatory figure showing the exposure device 3Aaccording to this embodiment. The dumper 560 is provided at a positionwhich is between the collimator mirror 510A and the fly-eye mirror array520, and moreover at the position at which the other non-EUV radiation302 which is separated out by the mirror 510A which is endowed with thefunction of acting as a SPF is collected together. This dumper 560absorbs the radiation 302, such as the laser radiation, in wavelengthregions other than the EUV radiation, which has been deflected by theblazed grooves 513, and converts it to thermal energy. It is desirablefor the dumper 560 to be cooled by some cooling mechanism such as awater cooling jacket or the like. On the other hand, for the EUVradiation 203, the mirror 510A functions like a C2 mirror in the priorart, and reflects this EUV radiation 203 and converts it to parallelradiation 204.

FIG. 12 is an explanatory figure showing the collimator mirror 510A inmagnified view. The blazed grooves 513 in this second embodiment aredifferent from the blazed grooves of the first embodiment shown in FIG.6, in that, as shown in FIG. 12, they are formed so that their abruptstep portions face away from the center of the mirror towards its outeredge. To express this in another manner, each of the blazed grooves 513is formed so that its sloping portion inclines relatively gently fromthe outside of the mirror towards the center of the mirror. Moreover, asshown in the plan view of FIG. 13, the blazed grooves 513 of this secondembodiment are formed as concentric circles.

Since the operation of the collimator mirror 510A is the same as in thecase of the first embodiment, it will be explained with reference toFIG. 4. In this embodiment, a total of 850 of the Mo/Si pair layers arelaid over one another upon the substrate portion 511. If the thicknessof one of these pair layers is taken as being 6.9 nm, then the dimensionHO is 5.865 μm. And, in this embodiment, the blazed grooves 513 areformed at a pitch of 400 μm through the upper 800 pair layers (so that,in this case, their thickness is 5.520 μm). As a result, the angle θBbecomes 13.8 mrad, so that 2θB is 27.6 mrad.

If the angle of incidence of the radiation 203 which is incident uponthis collimator mirror 510A is termed α, then the EUV radiation 204 isreflected at the angle α towards the fly-eye mirror array 520, while theDUV, UV, VIS, and IR radiation 302A such as the laser radiation etc. isregularly reflected at the angle α+2θB.

The IR radiation such as the CO₂ laser radiation and so on is diffracted(302B) at an angle of α+θD (or α−θD) by the blazed grooves (which havepitch of 400 μm). In this embodiment θd is 27.6 mrad, because thewavelength of the CO₂ laser is set to be 10.6 μm.

Although for convenience this feature is not shown in the figures, theDUV, UV, and VIS radiation are diffracted by the gratings which areformed by the periodic stripes of silicon and molybdenum appearing onthe front surfaces of the blazed grooves 513 (which in this embodimentare at a pitch of 0.5 μm), and proceed onward at angles which aredifferent from that of the EUV radiation 204. Accordingly, with thissecond embodiment having the above structure, it is possible to obtainsimilar beneficial effects to those obtained in the case of the firstembodiment. In this connection, in the same way as with the firstembodiment, it would also be acceptable to strengthen the advantageouseffect of action as a SPF by adding, to the configuration of this secondembodiment, a pinhole array 530 which is positioned at the location ofthe focus point group which is formed by the fly-eye mirror array 520,thus intercepting the radiation 302 other than the EUV radiation withthe wall portion of the pinhole array 530.

Embodiment 3

A third embodiment will now be explained on the basis of FIG. 14. FIG.14 is an explanatory figure showing the structure of an exposure device3B according to this embodiment. In this embodiment, blazed grooves areformed upon an inlet mirror 570 upon which the radiation from the EUVlight source device 2 is initially incident. The collimator mirror 510Bof this embodiment is different from the collimator mirrors 510 and 510Aof the embodiments described above, in that no blazed grooves areprovided thereupon. In other words, the collector mirror 510B of thisembodiment is a mirror which simply reflects radiation which is incidentonto it into parallel radiation, but is not endowed with the function ofoperating as an SPF.

A plurality of parallel blazed grooves are formed upon the inlet mirror570, just as was the case with the collimator mirror 510 described withreference to the first embodiment. In other words, the inlet mirror 570is made by laminating 300 pair layers of Mo/Si upon a flat platesubstrate, and by leaving the lowermost 50 of these pair layers just asthey are, while forming blazed grooves in the uppermost 250 pair layers.

Furthermore, in this embodiment, a second fly-eye mirror array 580 isprovided upon the optical path between the fly-eye mirror array 530 andthe condenser mirror 540. A pinhole array 530A is arranged so as to bepositioned quite close to this second fly-eye mirror array 580. In thisembodiment, by providing the plurality of fly-eye mirror arrays 530 and580, it is possible to make the intensity of the EUV radiation which isincident upon the mask 600 uniform in an even more effective manner.

The EUV radiation is reflected by the second fly-eye mirror array 580and is incident upon the condenser mirror 540. By contrast, theradiation 302 other than the EUV radiation, after having been reflectedby the first fly-eye mirror array 530, is intercepted by the pinholearray 530A which gets in its way, and is converted into heat.

With this embodiment having the structure described above, similarbeneficial effects are obtained as in the case of the other embodimentsdescribed above. However, with this embodiment, since the inlet mirror570 which is newly added is the one which is endowed with the functionof acting as an SPF, accordingly the number of reflections is increasedby one. Thus, the amount of EUV radiation which is incident upon themask 600 is somewhat decreased, as compared with the other embodimentsdescribed above. However, since this inlet mirror 570 of this embodimentis made as a planar mirror, accordingly it is simpler and easier tomanufacture as compared with the collector mirrors of the first andsecond embodiments described above, and it is possible to reduce itsmanufacturing cost.

Embodiment 4

A fourth embodiment will now be explained on the basis of FIG. 15. Theexposure device 3C of this fourth embodiment is provided with an inletmirror 570C which is made as a planar mirror, in a similar manner to thethird embodiment described above. However, on this inlet mirror 570C,the direction of the blazed grooves is changed to be similar to that inthe second embodiment. On this inlet mirror 570C, the blazed grooves areformed as concentric circles, as shown in FIG. 13. Moreover, in thisexposure device 3C, a dumper 561 is provided between the collimatormirror 510B and the fly-eye mirror array 530.

In this embodiment, due to the provision of the planar mirror 570C, thedirection of progression of the EUV radiation and the direction ofprogression of the radiation of other wavelengths are different, and theradiation 302 of other wavelengths is absorbed by the dumper 561. Thus,with this fourth embodiment having the structure described above,similar beneficial operational effects are obtained, as with the thirdembodiment described above.

Embodiment 5

A fifth embodiment will now be explained on the basis of FIG. 16. Thisinvolves a method of manufacturing the mirror 510A of the secondembodiment, which is endowed with the function of acting as an SPF.

As shown in FIG. 16( a), a mirror member 137 which is made by coating apredetermined number of composite pair layers upon a substrate portionis loaded upon a rotational stage 400 and is rotated. And a cuttingprocess for forming blazed grooves is performed by irradiating an ionbeam 430 upon these composite pair layers, using an ion milling device410 and a mask 420.

And, as shown in FIG. 16( b), a pattern 421 shaped as a right angledtriangle, and through which the ion beam 430 passes, is formed in themask 420. Accordingly, the width P of the blazed grooves (see FIG. 4)can be adjusted by changing the relative positional relationship betweenthe pattern 421 and the ion beam 430, so as to be, for example, like P1or P2 shown in FIG. 16( b).

As shown on the left side of FIG. 16( b), when the area of overlapbetween the triangular shaped pattern 421 and the ion beam 430 is small,it is possible to form narrow blazed grooves of width P1 as shown at thelower portion of this figure. On the other hand, as shown on the rightside of FIG. 16( b), when the ion beam 430 is overlapped over the entiresurface of the triangular shaped pattern 421, it is possible to formbroad blazed grooves of width P2.

Each time the formation of one blazed groove has been completed, the ionmilling device 410 and the mask 420 are shifted in the radial direction(the horizontal direction in FIG. 16) by just the desired pitch for thegrooves, and then the ion beam is again irradiated and a new blazedgroove is formed.

If blazed grooves like those shown in FIG. 4 are to be formed, then, asshown in FIG. 16( c), a mask 420 is used in which the orientation of thetriangular shaped pattern 421 is changed. Thus, with this embodiment ofthe present invention having the structure described above, it ispossible to manufacture the collimation mirror 510A described aboveaccording to the second embodiment, in a simple and easy manner.

In the case of the collimator mirror 510 described in connection withthe first embodiment, the mirror member 137 with the multi layerattached is not loaded upon a rotational stage 400 and rotated in the Fdirection as in described in connection with this embodiment; rather, itcan be made by the following method. It is possible to manufacture thecollimator mirror 510 of the first embodiment by loading the mirrormember 137 upon a two-axis type orthogonal stage which is shiftable inthe horizontal direction and shifting it linearly, so as to processrectilinear grooves into it. Moreover, the mirrors 570 and 570Cdescribed in connection with the third and the fourth embodiments can bemade by substantially the same manufacturing method as that describedabove, the only difference being the feature that the mirror member 137is planar.

Embodiment 6

A sixth embodiment will now be explained on the basis of FIG. 17. Thissixth embodiment is one which is effective if the mirrored surface ofthe mirror member 137 with the multi layer attached thereon is a curvedsurface. For example, when manufacturing the collimator mirror 510A ofthe second embodiment which has a curved surface, the ion milling device410 and the mask 420 are swung around a rotational axis 412 which ispositioned to correspond to the focus point at which the radiation 302other than the EUV radiation is to be gathered together.

The ion milling device 410 and the mask 420 are fitted to a long tubularsupport device 411 so as to be shiftable along its axial direction. Thissupport device 411 is rotatable in the left and right directions in FIG.17 about the rotational axis 412 as a center. The rotational axis 412 isset to a distance which is separated from the center of the mirrorsurface of the mirror member 137 (i.e. from where the center of themirror surface will be when it is completed) by just the distancedesired for the focus point IF. Then the blazed grooves are formed whileswinging the ion milling device 410 and the mask 420 axially in thesideways direction in the figure.

The rotational axis 412 is set to the same position with respect to thecollimation mirror 510A as the position at which the focus point forcondensation of the radiation reflected by the mirror 510A other thanthe EUV radiation will be located. Due to this, it is possible to keepthe angle at which the ion beam is incident upon the multi layerconstant, and thus it is possible to process the blazed grooves in aconstant shape in a stable manner. This means that it is possible toprevent shadow areas occurring upon the collimation mirror 510A, inwhich the EUV radiation is hindered by the edges of the blazed groovesand cannot be properly incident.

In a similar manner, it would also be possible to make the rotationalaxis 412 and the center of curvature of the mirror surface which isbeing processed coincide with one another. Even if the rotational axisis made to agree with the center of curvature of the mirror which isbeing processed in this manner, this is effective for making it possibleto keep the angle at which the ion beam is incident upon the multi layerconstant, so that it is possible to process the blazed grooves inconstant shapes in a stable manner. Moreover, the collimator mirror 510described with reference to the first embodiment may be manufactured byloading the mirror member 137 with the multi layer attached thereto upona two-axis orthogonal stage which can be shifted in the horizontaldirection, and by thus processing the grooves into the shapes ofstraight lines, instead of by loading the mirror member 137 upon therotational stage 400 and rotating it.

Embodiment 7

A seventh embodiment, in which the mirror 510A which is endowed with thefunction of acting as a SPF is manufactured by a different method, willnow be explained on the basis of FIG. 18. In this seventh embodiment, asshown in FIG. 18( a), the position of the rotational axis 412 is set toa position which coincides with the center of curvature of the mirrorsurface. Moreover, as shown in FIG. 18( b), a mask 420A is used whoselength corresponds to the radius of the collimator mirror 510A, and apattern 421, consisting of a plurality of right angled trianglescorresponding to each of the blazed grooves which are to be formed, isprovided upon this long mask 420A. Accordingly, it is possible to formthe blazed grooves by simply irradiating the ion beam while swinging theion milling device 410 in the diametrical direction and while rotatingthe mirror 510A, without any necessity for shifting the mask 420A.

With this seventh embodiment of the present invention having thestructure described above, it is again possible to prevent theoccurrence of so called shadow portions such as described above, just asin the case of the sixth embodiment described above, and it is thuspossible to provide a collimator mirror 510A which condenses andseparates out the EUV radiation with good efficiency. Moreover, sincethe angle at which the ion beam is incident upon the multi layer is keptconstant, and moreover since the distance between the mask 420A and thesurface of the mirror is kept constant, accordingly it is possible toprocess the blazed grooves in more constant shapes, in a stabilizedmanner. Furthermore, it would also be possible to manufacture thecollimator mirror 510 described with reference to the first embodimentby loading the mirror member 137 with the multi layer attached theretoupon a two-axis orthogonal stage which can be shifted in the horizontaldirection, and by thus processing the grooves into the shape of straightlines, instead of by loading the mirror member 137 upon the rotationalstage 400 and rotating it. Yet further, it would be possible tomanufacture the mirror 570 and the mirror 570C described above withreference to the third and the fourth embodiment respectively, bysubstantially the same method as the manufacturing method describedabove, with the point of difference being that the mirror member 137 isa planar surface.

Embodiment 8

An eighth embodiment of the present invention will now be explained onthe basis of FIG. 19. On the mirror 510C of this eighth embodiment,instead of blazed grooves, triangular roof-like grooves 513C areprovided. And, in this mirror 510C of this eighth embodiment, thesetriangular roof-like grooves 513C are, again, formed integrally in amulti layer which covers the front surface of the substrate portion 511.In a similar manner to the procedure for the first embodiment, in thisembodiment as well, for example, 300 pair layers of Mo/Si are layeredtogether into a multi layer on the substrate portion 511, and then thetriangular roof-like grooves or triangular roof shapes are formed in theuppermost 250 of these 300 pair layers, from the front surface inwards.In FIG. 19, the axial lines AX1 a and AX1 b are perpendiculars to thesubstrate portion 511, while the other axial lines AX2 a and AX2 b areaxes which are perpendicular to the sloping roof-shaped surfaces of thetriangular roof-like grooves 513C.

Each of these triangular roof-like grooves 513C has two sloping surfaces513C1 and 513C2. The tilt angles Ob2 of these two sloping surfaces 513C1and 513C2 may be set to be the same. Here, for convenience ofexplanation, the sloping surfaces on the left side in FIG. 19 will betermed the first sloping surfaces 513C1, while the sloping surfaces onthe right side in FIG. 13 will be termed the second sloping surfaces513C2.

The triangular roof-like grooves 513C, for example, may be formed at apitch P10 of around 800 μm. In this case, the first sloping surfaces513C1 and the second sloping surfaces 513C2 are defined alternatingly atintervals of 400 μm (which=P10/2) in the direction parallel to thesubstrate portion 511. To put this in another manner, with thecollimator mirror 510C of this embodiment, the orientations of thesloping surfaces 513C1 and 513C2 change to and fro in opposite senses atthis pitch P10/2.

According to the inclinations of the sloping surfaces 513C1 and 513C2,the radiation other than the EUV radiation (i.e. the driver laserradiation, and DUV, UV, VIS, and IR) is regularly reflected by thesesloping surfaces, and is directed in directions which are different fromthat of the reflected EUV radiation 204. The EUV radiation is Braggdiffracted by the foundation portion 512 and by the 10 to 50 Mo/Si pairlayers which are laid thereupon underneath the portion in which thetriangular roof-like grooves 513C are formed. The efficiency of thisdiffraction is the same as that of a mirror upon which Mo/Si pair layersare provided.

Furthermore, due to the triangular roof-like grating structure having aperiod of 800 μm which is defined, the VIS and IR radiation describedabove are diffracted in directions which are different from that of theEUV radiation. Moreover, due to the gratings which are defined by theperiodic stripe patterns of the Mo/Si pair layers which are exposed uponthe sloping surfaces 513C1 and 513C2, the radiation of comparativelyshort wavelengths other than the EUV radiation and the IR radiation(i.e. the DUV, UV, and VIS) is diffracted in directions which aredifferent from that of the reflected EUV radiation 204.

It would also be acceptable to arrange to set the value of the pitch P10to some other value such as 400 μm or the like, instead of to 800 μm.Furthermore, it is not necessary to keep the pitch constant; it wouldalso be acceptable to change the pitch according to the position inwhich the triangular roof-like grooves 513C are formed. Moreover, itwould also be possible to set the pitch of the sloping surfaces 513C1and the pitch of the sloping surfaces 513C2 to be different: forexample, the pitch of the sloping surfaces 513C1 might be set to 300 μmand the pitch of the sloping surfaces 513C2 might be set to 500 μm. Byinstalling a mirror of the structure described in this embodiment to theillumination optical system 500, it is possible to obtain similarbeneficial operational effects, as in the cases of the first through thefourth embodiments described above.

Embodiment 9

A ninth embodiment will now be explained on the basis of FIG. 20. Themirror 510D of this ninth embodiment is formed with relatively smoothundulating wave-like grooves 513D. The wave-like shape of these grooves513D may, for example, be, at least approximately, a sinusoidal shape.In this embodiment as well, for example, 300 Mo/Si pair layers arelaminated upon the foundation 511 as a multi layer, and then thewave-like grooves 513D are formed in the uppermost 250 of these pairlayers, from the front surface. In FIG. 20, the axial lines AX1L andAX1R are lines which are perpendicular to the substrate portion 511,while the other axial lines AX2L and AX2R are lines which areperpendicular to the arcuate surfaces at their steepest points. Thereference symbol 513D1 denotes a summit of one of the wave-like shapes,while the reference symbol 513D2 denotes a valley thereof.

With the mirror 510D according to this embodiment, the inclination ofthe surface changes relatively smoothly in a sinusoidal fashionrepeatedly at the pitch P10 (which may be, for example, 600 μm).According to the inclinations of the arcuate surfaces, the radiationother than the EUV radiation (i.e. the driver laser radiation, and theDUV, UV, VIS, and IR) is reflected in a direction which is differentfrom that of the reflected EUV radiation 204.

However at places when these inclinations are nearly horizontal, as atthe summit 513D1, and close to these places, the EUV radiation and theradiation other than the EUV radiation (i.e. the driver laser radiation,and the DUV, UV, VIS, and IR) are all regularly reflected inapproximately the same direction.

As described above, the EUV radiation is Bragg diffracted by thefoundation portion 511 and by the 10 to 50 Mo/Si pair layers which lieunderneath the portion in which the wave-like grooves 513D are formed.The efficiency of this diffraction is the same as that of a mirror uponwhich Mo/Si pair layers are provided. Furthermore, due to the wave-likegrating structure having, for example, a period of 600 μm, the radiationother than the EUV radiation is diffracted in directions which aredifferent from that of the EUV radiation. Moreover, due to the gratingwhich is defined by the periodic stripe pattern of the Mo/Si pair layerswhich are exposed upon the arcuate surfaces, the radiation ofcomparatively short wavelengths other than the EUV radiation and the IRradiation (i.e. the DUV, UV, and VIS) is diffracted in directions whichare different from that of the reflected EUV radiation 204.

By installing a mirror of the structure described in this embodiment tothe illumination optical system 500, it is possible to obtain similarbeneficial operational effects, as in the cases of the first through thefourth embodiments described above.

Embodiment 10

A tenth embodiment will now be explained on the basis of FIG. 21. Inthis tenth embodiment, a plane mirror 190 having a structure like thatdescribed with reference to FIG. 4 is provided within the EUV lightsource device 2A. The EUV radiation which is reflected by this planemirror 190 passes through an aperture member 160, and is supplied to theexposure device. The radiation 302 other than EUV radiation is reflectedby the plane mirror 190 and is incident upon the aperture member 160,and is absorbed by the aperture member and is converted to heat. It isdesirable for the angle of incidence of the EUV radiation 203 upon theplane mirror 190 to be kept less than or equal to around 30°, as shownusing FIG. 8.

Embodiment 11

An eleventh embodiment will now be explained on the basis of FIG. 22. Inthis eleventh embodiment, a concave surface mirror 191 having astructure like that described with reference to FIG. 4 is providedwithin the second chamber 102B of the EUV light source device 2B. TheEUV radiation 203 which is incident through the aperture member 160 intothe second chamber 102B is reflected by this concave surface mirror 191(204), and passes through an another aperture member 161 and is suppliedto the exposure device. The radiation other than EUV radiation isreflected (302) by the concave surface mirror 191 and is incident uponthe aperture member 161 and is absorbed thereby. It is desirable for theangle of incidence of the EUV radiation 203 upon the concave surfacemirror 191 to be kept less than or equal to around 30°, as shown usingFIG. 8.

It should be understood that the present invention is not limited to theembodiments described above. On the basis of the disclosure herein, aperson of ordinary skill in the art would be able to make variousadditions and/or changes and so on to the details of any particularembodiment, within the scope of the present invention. For example, itwould also be acceptable to provide a structure in which mirrors uponwhich multiple Mo/Si pair layers formed with grooves of predeterminedshapes were provided both to the exposure device and also to the EUVlight source device.

The invention claimed is:
 1. A semiconductor exposure device comprising:an illumination optical system configured to direct EUV (extremeultraviolet) light from an EUV light source to a mask; and mirrorsincluded in the illumination optical system, one of the mirrorscomprising a multilayered reflecting coating with grooves and beingconfigured to reflect the EUV light from the EUV light source to directthe EUV light to the mask, the grooves being arranged in parallel lines,wherein: the EUV light source is configured to irradiate a target withlaser light from a driver laser to turn the target into plasma fromwhich the EUV light is emitted, and the grooves are configured todiffract at least light at a wavelength which is the same as that of thelaser light from the drive laser.
 2. The semiconductor exposure deviceaccording to claim 1, wherein the one of the mirrors is a collimatormirror.
 3. The semiconductor exposure device according to claim 1,further comprising: a mirror array having concave surfaces configured toreflect the EUV light reflected by the one of the mirrors to gather theEUV light at intermediate focal points; a pinhole array formed withpinholes arranged at the intermediate focal points, and configured topass the EUV light reflected by the mirror array therethrough andintercept the at least light at the wavelength which is the same as thatof the laser light from the drive laser.
 4. The semiconductor exposuredevice according to claim 1, wherein the one of the mirrors is placed tofirst receive the EUV light from the EUV light source.
 5. Thesemiconductor exposure device according to claim 1, wherein thewavelength of the light to be diffracted by the grooves is approximately10.6 μm.
 6. The semiconductor exposure device according to claim 1,wherein the driver laser is a carbon dioxide (CO₂) laser.
 7. Thesemiconductor exposure device according to claim 1, wherein a distancebetween a nadir of one groove and that of an adjacent groove is in arange of 1.54 μm to 400 μm.
 8. The semiconductor exposure deviceaccording to claim 1, wherein a distance between a nadir of one grooveand that of an adjacent groove is in a range of 400 μm to 800 μm.
 9. Thesemiconductor exposure device according to claim 1, wherein a distancebetween a nadir of one groove and that of an adjacent groove is in arange of 1.54 μm to 800 μm.
 10. The semiconductor exposure deviceaccording to claim 1, further comprising a dumper for light to bediffracted by the grooves.
 11. The semiconductor exposure deviceaccording to claim 10, further comprising a cooling device for coolingthe dumper.
 12. The semiconductor exposure device according to claim 10,wherein the wavelength of the light to be diffracted by the grooves isapproximately 10.6 μm.
 13. The semiconductor exposure device accordingto claim 10, wherein the light to be diffracted by the grooves is laserlight from a carbon dioxide (CO₂) laser for generating the EUV light.14. The semiconductor exposure device according to claim 1, wherein themultilayered reflecting coating comprises 100 to 1000 pairs of stackedMo/Si layers.
 15. The semiconductor exposure device according to claim1, wherein the multilayered reflecting coating comprises pairs ofstacked Mo/Si layers, and a nadir of each groove reaches approximately250th to 300th pair of the stacked Mo/Si layers from a surface of theone of the mirrors.
 16. The semiconductor exposure device according toclaim 1, wherein the one of the mirrors comprises a substrate having themultilayered reflecting coating thereon, the multilayered reflectingcoating comprises pairs of stacked Mo/Si layers, and the multilayeredreflecting coating includes approximately 50 pairs of the stacked Mo/Silayers between the nadir and the substrate.
 17. The semiconductorexposure device according to claim 1, further comprising a surfacecoating on a surface of the multilayered reflecting coating.
 18. Thesemiconductor exposure device according to claim 17, wherein a materialof the surface coating includes ruthenium.
 19. The semiconductorexposure device according to claim 1, wherein the multilayeredreflecting coating is formed with grooves having triangular roof shapesin a sectional view of the one of the mirrors.
 20. The semiconductorexposure device according to claim 1, wherein the multilayeredreflecting coating is formed with grooves having wave-like shapes in asectional view of the one of the mirrors.